Speaker
Description
Black hole low-mass X-ray binaries (BH LMXBs) are transient sources which spend most of their lifetime in quiescent states. Once or twice a year they are characterised by bright outbursts that last for days to months, during which accretion flow, compact jets and discrete ejecta undergo significant evolution. These relatively short outburst timescales make BH LMXBs ideal natural laboratories for time-evolution studies of jets and accretion flows. GX 339-4 is a Galactic black hole X-ray binary that was discovered in 1973 and studied in detail ever since. It was recorded transitioning from hard to soft X-ray state in 2024 January. In this paper, we present weekly and daily MeerKAT radio monitoring of this system, showing the evolution of the radio light
curve during its transition. Our radio observations show the early steady rise and subsequent quenching of the compact jet as the outburst brightened and then evolved toward the soft state exhibiting an optically thin radio flare. We constrain the compact jet quenching factor to be several orders of magnitude. The spectral index changes from flat spectra to steep spectra. We also determine significant linear polarisation as well as constant values of the electric vector position angle. These results are consistent with a transformation from a self-absorbed compact jet to optically thin ejecta.
| Talk category | Plenary |
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